Studies indicate an increase in cancer cases among people under 50 — Photo: Adobe Stock
Over the past 20 years, cancer cases have increased worldwide. Diagnosis has increased mainly among the younger population. Colorectal, or bowel, cancer was one of the most advanced cancers. In 2001, around one in every 26,000 people under the age of 50 in England received this diagnosis. In 2023, this rate rose to around one in every 12 thousand people, double the figure recorded two decades ago.
This data comes from the World Cancer Research Fund (WCRF), an international network of charitable organizations that analyzed records from England, the United States and the Netherlands. The organization found that the number of new cases increased to seven types of cancer in England alone.
It is not yet clear, however, whether there has been an increase in actual cases or whether more cases have been identified at an early stage due to greater awareness, earlier diagnosis and treatment in hospitals.
And, despite the growth, the total number of cases is still small, as pointed out by Amy Berrington de Gonzalez, professor of clinical epidemiology at the Institute of Cancer Research, in London. "Cancer is still very uncommon among young people. Three times a small number remains a small number."
Early-onset cancer rates rise in Latin America
A 2025 study analyzed registry data from 50 countries and territories through 2017. Researchers found increased cases of early-onset colorectal cancer in 27 of those regions. In Latin America, rates increased in Chile, Argentina, Ecuador, Costa Rica and Puerto Rico. The increase observed in Chile, of almost 4% per year, was among the highest.
The National Cancer Institute (Inca) estimates 781 thousand new cases of cancer per year in Brazil between 2026 and 2028, with emphasis on cervical and colorectal cancers, types with great potential for prevention and early detection.
Marc Gunter, professor of cancer epidemiology at Imperial College London, points out changes in the eating pattern in Latin America, increasingly based on ultra-processed foods, and a more sedentary lifestyle as possible causes of the disease's progression.
The six types of cancer that most affect young adults
In another study, published in 2025, involving 42 countries, Berrington de Gonzalez compared data from two age groups, 20 to 49 years old and 50 years old and over, between 2003 and 2017.
Six types of cancer – thyroid, breast, colorectal, kidney, uterine and leukemia – showed an increase among younger groups in most countries. All but colorectal cancer also saw growth among older adults.
In fact, colorectal cancer stood out. In about a third of the countries analyzed, it increased more quickly among young adults than among older ones. "It's the only cancer that appears to be increasing among young people while decreasing among older people," said Berrington de Gonzalez.
This has consequences for scientific research. If cancer cases are increasing across all age groups, it is likely that the causes are widespread. Therefore, studies focusing only on young people run the risk of seeking complex explanations without having sufficient data to test them, said the researcher.
Greater awareness may explain increase in diagnoses
An American study of pancreatic cancer in people aged 15 to 39 found that growth occurred almost exclusively in tumors diagnosed at an early stage. Death rates remained unchanged.
This suggests that, rather than an increase in the number of cancer cases, there has been an increase in the number of early diagnoses. And this can be explained by greater awareness among the population, leading more people to take exams.
The data on colorectal cancer, however, appears different: some American studies also show an increase in the advanced stages of the disease, which suggests a real increase in the number of cases, and not just diagnoses.
Relationship between cancer and obesity
Obesity is a proven cause of at least 13 types of cancer, according to the International Agency for Research on Cancer (IARC), of the World Health Organization (WHO). According to a review of studies published in 2021, young adults with obesity were almost twice as likely to develop colorectal cancer before age 50.
Obesity was also the condition that spread most quickly among young people. The WHO reports that obesity rates have doubled among adults since the 1990s and quadrupled among adolescents.
Furthermore, food makes a difference. Processed meats are classified as carcinogenic. Alcohol consumption is also a risk factor. A diet rich in fiber (present in vegetables, whole grains and legumes) reduces the risk of cancer.
Some researchers also claim that ultra-processed foods and microplastics cause cancer. But Gunter said the evidence is still inconclusive. "There's a lot of hype around the topic," Gunter said, adding that more research is needed. Berrington de Gonzalez agrees: "Diets have changed, but we don't yet know what role that might play."
How young people can reduce cancer risk
Gunter said people should not be blamed for living in societies structured around convenient food and sedentary work, and that lasting change depends on public health policies.
But he also said young people can reduce their cancer risk by maintaining a healthy weight, getting more physical activity, consuming more fiber and reducing their consumption of processed meats. "Go for a walk, be more physically active, eat more fruits and vegetables. Maybe these things aren't as trendy, but they're really important."
For a 30-year-old reading this report, Berrington de Gonzalez's message is reassuring: cancer among young people remains relatively rare.
